Device for crushing hot furnace discharge material, particularly hot alumina

ABSTRACT

A device for crushing hot alumina is arranged between the discharge aperture of a calcining furnace and the charging aperture of a cooler and comprises a primary crushing roller arranged in a vertical discharge channel between the ends thereof and a pneumatic crushing means connected to the lower end of said discharge channel, whereby the outlet of said pneumatic crushing means is connected with a separator which in turn is connected with said cooler.

Elniiied States Patent [191 Weigel et a1.

[54] DEVECE FQR CRUSHENG HGT FURNACE DISQHARGE MATERIAL, PAR'HCULARLYHUT ALUMINA T51 15665165 F nnsrwe'i zi; 6m Wilberti Theo Manshausen;Alfred Kryczun, all of JM QQ Ge y [73] Assignee: Klockner-Humboldt-DentzAktiengesellschaft, Cologne, Germany [22] Filed: Sept. 7, 1971 [21]Appl. No.: 178,269

[30] Foreign Application Priority Data Sept. 18, 1970 Germany ..P 20 46136.3

[52] U.S. Cl. ..241/40, 241/44, 241/75, 241/135, 241/152 A [51] int. C1...B02c 25/00 [58] Field of Search ..241/40, 44, 57, 62,

[11] 3,734,434 51 May 22, E973 [56] References Cited UNITED STATESPATENTS 1,189,122 6/1916 Keller ..241/13$ 1,407,330 2/1922 Hiller..241/l35 X 2,652,984 9/1953 Dodds ..24l/135 2,853,241 9/1958 Gindoff eta1 ..241/40 X Attorney-Hill, Sherman, Meroni, Gross & Simpson [57]ABSTRACT A device for crushing hot alumina is arranged between thedischarge aperture of a calcining furnace and the charging aperture of acooler and comprises a primary crushing roller arranged in a verticaldischarge channel between the ends thereof and a pneumatic crushingmeans connected to the lower end of said discharge channel, whereby theoutlet of said pneumatic crushing means is connected with a separatorwhich in turn is connected with said cooler.

rimq'y mmine am V l Crater is 12 Claims, 2 Drawing Figures DEVICE FORCRUSHING HOT FURNACE DISCHARGE MATERIAL, PARTICULARLY HOT ALUMINA Theinvention relates to a device for the crushing of hot furnace dischargematerial, particularly hot alumina, which device is arranged between thematerial discharge aperture of a calcining furnace and the chargingaperture of a cooling device.

During the calcination of alumina in a rotary furnace are producedfrequently, owing to locally occurring sintering phenomena, more or lesslarge nodules in the otherwise fine-grained material. These nodules, inview of their size and their relatively high weight, cannot pass throughthe customary employed vortex bed coolers or standpipe coolers.Particularly when employing vortex bed coolers the mentioned nodules area disadvantage because they obstruct the passage of the material.

The U.S. Pat. No. 2,905,395 discloses a crushing device in which atransfer chamber is arranged directly after a rotary furnace between thedischarge end of the furnace and the charging aperture of the followingstandpipe cooler. This crushing device comprises a screen arranged at aninclination and over which the entire furnace discharge is passed forthe separation of the fine-grained material from the nodules. At the endof the screen layer is arranged a two roller crusher which has thepurpose for crushing the nodules which are discharged by the furnace.This known device has the disadvantage that for the purpose of asufficient crushing the gap between the two crushing rolls has to besmall. This has, however, the result that the larger nodules are onlypoorly drawn into the gap so that either a greater gap has to be chosen,or one has to employ larger rolls. A larger gap results, however, in aninsufficient crushing operation, while larger rolls are substantiallymore expensive. Since the material discharged by the furnace containsfrequently fragments of the furnace wall which compared with thematerial nodules are very hard, it is necessary to support at least oneof the rolls yieldably so that the rolls of the crushing device areprotected against injury. Owing to the high temperature of the materialdischarged by the furnace, approximately 1,200 C, such a crushing devicebecomes very complicated and expensive.

Considering the above-mentioned disadvantages of the known device, theobject of the invention is to arrange between the material dischargeopening of a calcining furnace and the charging aperture of a coolingdevice a crushing device for the hot material coming from the furnace,particularly hot alumina, which device is distinguished by a materialdischarge channel in which is arranged a rotary primary crushing rollwhich is provided with substantially radial tappets and crushingelements and wherein the discharge channel below the mentioned primarycrushing roll merges into a pneumatic crushing device. The advantage ofthis device is that the crushing operation takes place in two steps andthat the primary crushing roll seizes large nodules more effectivelythan the known crushing device. Owing to the tappets and crushingelements which are arranged on the circumference of the roll, it ispossible to employ a roll with a relatively small diameter. Thecombination of the mechanically acting primary crushing roll with apneumatic crushing device results in an advantageous equalization of thematerial which frequently is discharged by separated thrusts from thefurnace. This is of importance for obtaining a good efficiency of vortexbed coolers or air-operated standpipe coolers. Since furthermore theentire amount of material discharged by the furnace is practicallyintroduced in a fine-grained condition from the furnace into the coolingdevice a substantially more favorable heat exchange is obtained so thatthe heat consumption of the entire calcining process is favorable.Another advantage resides in the fact that any fragments of the furnacewall which may be contained in the material discharged by the furnacemay pass the primary roll substantially unchanged and then may beseparated from the furnace material in the pneumatic crushing device.

According to the invention, the pneumatic crushing device comprises asubstantially horizontally extending guide tube into whichviewed in theflow direction of the gas-in advance of the merging point of thematerial discharge channel into the guide tube a driving nozzle for airor gas is inserted, while the guide tube in rear of the connection ofthe material discharge channel with the guide tube is provided with asharp bend or elbow and that after this bend the conduit is connectedwith a separator whose material discharge tube is connected with acooling device. The material discharged by the furnace and any smallnodules and non-crushed nodule particles in the same are picked up bythe air which passes at high speed from the driving nozzle and conveysthe same through the guide tube. In view of the sharp bend of the drivenair jet, the nodules and the non-crushed particles thereof and alsofragments of the furnace wall are catapulted against the wall of thebend. When this happens, the nodules are broken up and continue asfine-grained material toward the separator. The fragments of the furnacewall, however, remain in the bend and are constantly moved by the gasstream back and forth and thereby are frictionally comminuted byabrasion. Very hard pieces may be removed from time to time through aninspection aperture which normally is closed by a plate. The necessaryamounts of air for operating the pneumatic crushing device may be heldrelatively small owing to the employment of the drive nozzle so that inthe subsequent cooling process the hot discharged air volumes do nothave to be increased to any noticeable extent. On account of thisfeature the heat economy of the entire calcining method is veryfavorable.

The portion of the guide tube in rear of the bend and leading to theseparator is preferably positioned vertically and preferably has also alarger cross section as the horizontally disposed portion of the guidetube. This has the advantage that nodules and nodule particles, whichowing to a stronger sintering effect have not been crushed during thefirst catapulting, drop back into the bend and remain there until theyare completely comminuted by abrasion during their constant movement, sothat in this manner these parts are also crushed or comminutedcompletely within a very short period of time.

Another object of the invention is to provide the walls of the materialdischarge channel above the primary crushing roll with one or moreopenings for the introduction of air for the purpose of loosening thematerial which comes from the furnace. This has the advantage that acaking of the material is avoided, whose temperature directly in rear ofthe calcining furnace is still within the range of the sinteringtemperature.

Still another object of the invention is that the tappets and crushingelements of the primary crushing roll are constructed as straight barswhich substantially extend in the axial direction of the primarycrushing roll. This construction of the tappets and crushing elementsprovides the primary crushing roll with an additional dosing effectwhich initiates in cooperation with the pneumatic crushing operation apractically completely uniform flow the material toward the coolingdevice, so that for the cooling operation the optimum operatingcondition may be adjusted.

In accordance with still another object of the invention, the walls ofthe material discharge channel extending in the axial direction of theprimary crushing roll, are so curved that the same concentricallysurround both sides of the primary crushing roller. This featureimproves the dosing and crushing action of the primary crushing roll.Preferably, that portion of the wall of the material discharge channelwhich is located on the side of the upwardly directed rotary movement ofthe primary crushing roll surrounds the circumference of the primarycrushing roll along a longer distance as the oppositely disposed wallportion of the material discharge channel. This construction has theresult that on the side of the upwardly directed rotary movement of theprimary crushing roll, on which no material is located which comes fromthe furnace, an improved sealing effect is obtained.

According to a preferred embodiment of the crushing device, the materialdischarge channel is separated into two branch channels in each of whichis arranged a primary crushing roll. Each of these branch channels isprovided above the primary crushing roll therein with a locking gate,and such a construction makes it possihie-provided each primary crushingroll is so designed that it is able to accommodate the entire amount ofmaterial discharged by the furnaceto operate the device withoutinterruption in the event of damage or in the event that very largebrick fragments should block one of the two primary crushing rolls. Inthat event, one is able to make repairs on the inoperative primarycrushing roll, while the other primary crushing roll continues tooperate so that the furnace operation is not at all interrupted.

it is also an object of the invention to connect each primary crushingroll with a rotation monitor which closes automatically by means of anadjusting device the locking gate of the primary crushing roll which hasbeen blocked, whereby also the drive of the respective primary crushingroll is disconnected. This feature avoids a damage to the correspondingprimary crushing mi] and its drive motor, respectively.

When the device of the invention is equipped with two primary crushingrolls, preferably each rotation monitor is additionally connected with aswitching mechanism, which upon stoppage of one of the primary crushingrolls effects an operation of the other primary crushing roll. In thismanner, a continuous and troublefree furnace operation is assured.

With these and other objects in view, the invention will now bedescribed with reference to a specific example illustrated in thedrawings.

In the drawings:

FIG. 1 is an end view of the furnace discharge with a crushing devicepartly in vertical section, and

FIG. 2 illustrates on an enlarged scale one embodiment of a primarycrushing device in section.

Referring to FIG. 1, a vertical material discharge channel 2 extendsdownwardly from the lower portion of the furnace hood 1 of a rotaryfurnace employed for the calcination of alumina. This discharge channel2 is subdivided in two branch channels 3 and 4. In the branch channel 3is arranged a primary crushing roll 5 and in the branch channel 4 isarranged a primary crushing roll 6. Below the primary crushing roll isarranged an intermediate channel piece 7 in which the two branchchannels are again united to form a single channel. The lower dischargeaperture 8 of this intermediate channel member 7 is in communicationwith a horizontally disposed guide tube 9 through which air or gas flowswith high speed. Looking in the direction of the flow of the gas or air,there is arranged ahead of the discharge aperture 8 a drive nozzle 10through which air is introduced from a feed tube 11 which is acceleratedto a speed above 20 m/per sec. Viewed in the flow direction of thedriven air jet, there is arranged in rear of the discharge aperture 8,which transversely enters the guide tube 9, a bend 12 which deflects thedriven air jet laden with material from the discharge channel 7 aboutupwardly and into a vertical conveyor tube 13, which is preferablyinternally larger than the horizontal portion 9, and whose upper end isconnected with the upper end of a cyclone 14 in which the fine-grainedmaterial is separated from the driven air and by means of a dischargetube 15 is conducted into a cooling device 16. The heated driven airwhich is discharged by the upper end of the cyclone, in addition to thatportion which is withdrawn from the cooling device, is conducted assecondary air into the furnace by a pipe 17.

The crushing device of the invention operates in the following manner:Since the primary crushing rolls 5 and 6 are so designed that each rollis able to accommodate the entire amount of material discharged by thefurnace, one of the two locking gates 18, 19 arranged in the branchchannels 3, 4 is closed. The locking gates 18, 19 are arranged in saidbranch channels 3 and 4 above the primary crushing rolls therein. In thepresent instance, the branch channel 3 is closed by the locking gate 18.The fine-grained material together with the material nodules therein andwhich is discharged by the furnace is conducted by the branch channel 4to the crushing roll 6. The tappets and crushing elements 20 on thecircumference of this crushing roll draw the fine-grained material andnodules into the roll and those nodules which are thicker than theheight of the crushing elements are crushed. The primary crushing roll 6delivers the material to the common channel piece 7 and from the lowerend thereof the material is conducted through the aperture 8transversely into the horizontal guide tube 9.

The feed pipe 11 supplies air to the guide tube 9 and this air by meansof the drive nozzle 10 is accelerated to a speed of approximately 25mlper sec. The driven air jet pulls the material coming from the furnaceand discharged by the aperture 3 along with it. The length of the guidetube 9 between the aperture 8 and the bend 12 has to be determined to beof such a distance that the material coming from the furnace will begiven the highest possible acceleration so that a sufficient kineticenergy is available for the crushing operation. The fine-grained portionof the material, which comprises the largest portion of the materialcoming from the furnace, will pass the bend 12 without encountering anydifficulties and is conveyed by the driven air into the cyclone 14. Thenodules and nodule particles, which are not sufficiently crushed by theprimary crushing roll are, however, catapulted against the curved wallin the bend 12 and when this happens they are practically completelyconverted into fine-grained material particles, which are at once seizedby the driven air and are pulled upwardly in the conveyor tube 13. Thosenodules, however, which are sintered together to a higher degree andwhich do not disintegrate upon the first impact, are moved continuouslyback and forth by the driven air stream over the lower portion of thewall of the bend 12 and in this manner they are completely ground withina very short time. At the same time, the bend 12 will also cause agrinding of the fragments of the brick lining which may be contained inthe material coming from the furnace. Any pieces, however, which aredifficult to crush or ground may be removed from time to time through anormally closed inspection aperture 21 provided in the bend 12.

In order to assure an operation of the furnace without disturbances, theembodiment of the crushing device illustrated in FIG. 1 and providedwith two primary crushing rolls 5 and 6, is also provided with rotationmonitors 22 and 23, one for each of said primary crushing rolls. Theserotation monitors are connected by a suitable circuit with adjustingdevices 24 and 25, which operate the locking gates 18 and 19. Inaddition, the rotation monitors are each connected with a switchingmechanism 26 and 27 which connect the rotation monitors 22 and 23 witheach other. The arrangement is such that, for instance, when one of theprimary crushing rolls 6 should suddenly stop, for instance, byencountering a brick lining fragment of excessive size, then therotation monitor 22 closes by means of the adjusting device 24 thelocking gate 19. At the same time, the switching mechanisms 26 and 27cause the primary crushing roll 5 to be set in operation and by means ofthe adjusting device 25 the locking gate 18 in the branch channel 3 isopened so that no interruption of the furnace operation occurs.

A preferred arrangement for controlling the rotation of the crushingrolls is to provide a drive motor for each of said rolls. The drivemotor can be directly connected to the roll or connected through aclutch. For stopping the roll, the motor may be disconnected such as byturning off its power, or it may be disconnected by disengagement of theclutch. These conventional driving devices will be fully apparent tothose versed in the art.

Pipelines 28 are connected with the spaces above the primary crushingrolls in the material discharge channels 3 and 4 and blow justsufficient air into the channels 3 and 4 that the material in thesechannels is aerated and loosened up. In this manner a caking of thematerial coming from the furnace is prevented even though thetemperature of this material may still be in the range of the sinteringtemperature.

FIG. 2 illustrates on an enlarged scale and in section one of theprimary crushing rolls, namely roll 5. The primary crushing roll 5 isadvantageously arranged in a particularly-shaped channel portion 29,which by a flexible connection 30 is connected with the upper part ofthe material discharge channel, namely in this particular instance, withthe branch channel 3. The brick lining 31 of this material dischargechannel, in the range of the channel portion 29, is so shaped that thelining surrounds a portion of the circumference of the primary crushingroll concentrically. This portion of the brick lining is advantageouslyso shaped that the wall portion 32 on the side of the upwardly directedrotary movement of the primary crushing roll is surrounded to a greaterextent than the oppositely disposed wall portion 33. In this manner thewall portion 32 is more inclined above the primary crushing roll andeffects a good seal of the pneumatic crushing device with respect to thefurnace space. The other opposite wall portion 33, has above the primarycrushing roll a closeable inspection aperture 34 which permits theremoval of any blocking particles which may collect above the range ofthe primary crushing roll so that any disturbance in the operation canbe eliminated.

The primary crushing roll in the disclosed example is provided on itscircumference with radial tappets and crushing elements 20 which areconstructed as straight bars which extend substantially in axialdirection of the primary crushing roll. These bars effect a very gooddosing and a sufficient primary crushing of very large nodules whichwould be crushed with more difficulty in the pneumatic crushing device.In place of these long straight bars, one could also employ prongs orshorter bars which are offset with respect to one another.

What we claim is:

1. Device for crushing of hot furnace discharge material, particularlyhot alumina, arranged between the discharge aperture of a calciningfurnace and the charging aperture of a cooler, comprising means forminga vertical material discharge channel, a rotary primary crushing rollarranged in said discharge channel between the ends thereof, a pneumaticcrushing means arranged below said primary crushing roll and con-.

nected to the lower end of said vertical discharge channel whichdischarges the material which was crushed by said primary crushing roll,and means connecting said pneumatic crushing means with said cooler.

2. Device according to claim 1, in which said pneumatic crushing meansincludes a horizontally disposed guide tube into one end of whichextends a drive nozzle for introducing air lengthwise into said guidetube, said discharge channel being transversely connected with saidguide tube at a point where the air from said nozzle enters, said guidetube at a distance spaced from the point where the discharge channel isconnected to it being provided with a bend leading upwardly to the inletof a separator, and a discharge pipe for said separator leading to saidcooler.

3. Device according to claim 1, in which the wall of said dischargechannel above said primary crushing roll is provided with at least oneaperture for the feed of air into said channel for loosening thematerial coming from the furnace.

4. Device according to claim 1, in which the circumference of saidprimary crushing roll is provided with material crushing tappets in theform of bars extending lengthwise of said primary crushing roll.

5. Device according to claim 1, in which said primary crushing roll isof a size so as to fill the cross sectional area of said dischargechannel.

6. Device according to claim 5, in which wall portions of the dischargechannel surround concentrically opposite circumferential portions ofsaid primary crushing roll.

'7. Device according to claim 5, in which wall portions of the dischargechannel surround concentrically opposite circumferential portions ofsaid primary crushing roll, and the wall portion at the downwardlyrotating portion of said primary crushing roll surrounds said crushingroll along a longer circumferential portion of said primary crushingroll than on the opposite side of said roll.

8. Device according to claim 1, in which said material discharge channelis subdivided into two branch channels and that in each one of saidbranch channel is disposed a primary crushing roll.

9. Device according to claim 1, in which said material discharge channelis subdivided into two branch channels and that in each one of saidbranch channel is disposed a primary crushing roll, and a locking gateis positioned in each of said branch channels disposed above saidprimary crushing roll.

10. A device according to claim 9, including an rotation monitorconnected with each one of said primary crushing rolls, a drive motorfor each of said rolls, an adjusting means for each one of said rotationmonitors, the latter together with said adjusting means upon stoppage ofone of said primary crushing rolls causing a closure of the locking gateassociated with said stopped primary crushing roll and a disconnectionof the respective drive motor.

11. A device according to claim 9, including a rotation monitorconnected with each one of said primary crushing rolls, a drive motorfor each said rolls, an adjusting means for each one of said rotationmonitors, the latter together with said adjusting means upon stoppage ofone of said primary crushing rolls causing a closure of the locking gateassociated with said stopped primary crushing roll and a disconnectionof the respective drive motor, and an additional switching means foreach rotation monitor, said switching means upon stoppage of one of saidprimary crushing rolls causing an operation of the other one of saidprimary crushing roll and an opening of the locking gate connectedtherewith.

12. Device according to claim 2, in which the upwardly extending portionof said guide tube has a greater cross sectional area than saidhorizontally disposed guide tube.

1. Device for crushing of hot furnace discharge material, particularlyhot alumina, arranged between the discharge aperture of a calciningfurnace and the charging aperture of a cooler, comprising means forminga vertical material discharge channel, a rotary primary crushing rollarranged in said discharge channel between the ends thereof, a pneumaticcrushing means arranged below said primary crushing roll and connectedto the lower end of said vertical discharge channel which discharges thematerial which was crushed by said primary crushing roll, and meansconnecting said pneumatic crushing means with said cooler.
 2. Deviceaccording to claim 1, in which said pneumatic crushing means includes ahorizontally disposed guide tube into one end of which extends a drivenozzle for introducing air lengthwise into said guide tube, saiddischarge channel being transversely connected with said guide tube at apoint where the air from said nozzle enters, said guide tube at adistance spaced from the point where the discharge channel is connectedto it being provided with a bend leading upwardly to the inlet of aseparator, and a discharge pipe for said separator leading to saidcooler.
 3. Device according to claim 1, in which the wall of saiddischarge channel above said primary crushing roll is provided with atleast one aperture for the feed of air into said channel for looseningthe material coming from the furnace.
 4. Device according to claim 1, inwhich the circumference of said primary crushing roll is provided withmaterial crushing tappets in the form of bars extending lengthwise ofsaid primary crushing roll.
 5. Device according to claim 1, in whichsaid primary crushing roll is of a size so as to fill the crosssectional area of said discharge channel.
 6. Device according to claim5, in which wall portions of the discharge channel surroundconcentrically opposite circumferential portions of said primarycrushing roll.
 7. Device according to claim 5, in which wall portions ofthe discharge channel surround concentrically opposite circumferentialportions of said primary crushing roll, and the wall portion at thedownwardly rotating portion of said primary crushing roll surrounds saidcrushing roll along a longer circumferential portion of said primarycrushing roll than on the opposite side of said roll.
 8. Deviceaccording to claim 1, in which said material discharge channel issubdivided into two branch channels and that in each one of said branchchannel is disposed a primary crushing roll.
 9. Device according toclaim 1, in which said material discharge channel is subdivided into twobranch channels and that in each one of said branch channel is disposeda primary crushing roll, and a locking gate is positioned in each ofsaid branch channels disposed above said primary crushing roll.
 10. Adevice according to claim 9, including an rotation monitor connectedwith each one of said primary crushing rolls, a drive motor for each ofsaid rolls, an adjusting means for each one of said rotation monitors,the latter together with said adjusting means upon stoppage of one ofsaid primary crushing rolls causing a closure of the locking gateassociated with said stopped primary crushing roll and a disconnectionof the respective drive motor.
 11. A device according to claim 9,including a rotation monitor connected with each one of said primarycrushing rolls, a drive motor for each said rolls, an adjusting meansfor each one of said rotation monitors, the latter together with saidadjusting means upon stoppage of one of said primary crushing rollscausing a closure of the locking gate associated with said stoppedprimary crushing roll and a disconnection of the respective drive motor,and an additional switching means for each rotation monitor, saidswitching means upon stoppage of one of said primary crushing rollscausing an operation of the other one of said primary crushing roll andan opening of the locking gate Connected therewith.
 12. Device accordingto claim 2, in which the upwardly extending portion of said guide tubehas a greater cross sectional area than said horizontally disposed guidetube.